On impulsive pest control using integrated intervention strategies

How to use chemical and biological control in sensible combinations has been a concern of many agriculture departments and ecologists. To address this problem, a pest-natural enemy model with disease in the pest and with different frequencies of pesticide sprays and of releases of both infected pests and natural enemies is proposed and analyzed by using impulsive differential equations. The threshold conditions for susceptible pest (or total pest) eradication periodic solution are provided for different scenarios. In particular, two different natural enemy release strategies and two different pest control tactics are investigated and compared in detail. Furthermore, the effects of the frequency of pesticide applications and the frequency of natural enemy and infected pest releases on the threshold values are discussed. The results indicate that there exists an optimal frequency of pesticide application or an optimal releasing period which minimizes the threshold value. This information may help pest control experts to decide on the optimum timing for spray applications and optimum rates for releases.